Effect of nettle plant extract on the cementation of copper onto zinc in acidic sulfate solutions

• The cementation rate of copper onto zinc is favored by addition of nettle extract.
• 1.5 g L–1 of plant extract is the optimum value for inhibiting hydrogen evolution.
• Hydrogen reaction is the cause of the decrease of cementation reaction efficiency.
• The holes created by hydrogen evolution diminish in the presence of nettle extract.
• The cementation is an attractive way to recover copper by adding natural compounds.

The cementation of copper onto zinc in acidic sulfate solutions in the presence of nettle (Urtica Dioica L.) extract was studied using atomic absorption spectroscopy, scanning electron microscopy, EDX and voltammetry techniques. The extract obtained by refluxed technique in water, was shown to be a good inhibitor against hydrogen evolution. This hydrogen is the major cause of the overconsumption of the substrate during cementation in acidic media and limits the efficiency of the cementation reaction. The rate of cementation is improved by the increase of inhibitor concentration in the solution until an optimal value of 1.5 g L− 1. The rate of the cementation reaction was also found to increase with increasing temperature until 37 °C. This effect is more significant when the inhibitor is present in the solution. This improvement is due to the inhibition of the hydrogen evolution by adding nettle extract in the solution. The electrode potential E(t) changes during cementation, with and without nettle extract, are followed and some conclusions were drawn for the copper deposit adherence onto the substrate and its morphology.